conn = new Mongo("127.0.0.1:27017");
db = conn.getDB("all");

printjson(db.getCollection('addressHistory1807').update( {}, {$unset:{'serialNum':''}}, false, true));
printjson(db.getCollection('addressHistory1807').update( {}, {$unset:{'alarm':''}}, false, true));
printjson(db.getCollection('addressHistory1807').update( {}, {$unset:{'height':''}}, false, true));
printjson(db.getCollection('addressHistory1807').update( {}, {$unset:{'direction':''}}, false, true));
printjson(db.getCollection('addressHistory1807').update( {}, {$unset:{'upString':''}}, false, true));